This invention relates to a drive mechanism.

Drive mechanisms for transmission of torque from a drive shaft to a driven shaft are known. One such mechanism employs a number of sets of gears, the gears of each set being sized to intermesh directly at peripheral edges or via an interconnecting chain. The gears are sized to provide predetermined speed ratios and constant torque to the driven shaft on application of a predetermined torque to the drive shaft. Different speed ratio and torque requirements are accommodated by changing gears. The method of changing gears is relatively complicated and requires synchronisation of gears or use of a complex clutch system.

The present invention seeks to provide a simpler mechanism which allows for varying torque transmission and speed ratios between a drive member, such as a drive shaft, and a driven member, such as a cog.

In accordance with the present invention, there is provided a drive mechanism comprising: a drive member rotatable about a first axis; a driven member rotatable about a second axis; and a linkage interconnecting the members such that rotation of the drive member results in rotation of the driven member, wherein the linkage is fixed to the drive member for rotation about the first axis and is coupled to the driven member via a guide means which allows for movement of the linkage along a predetermined path relative to the second axis, and wherein the members are adapted to be positioned such that the first and second axis are substantially parallel and spaced apart whereby the linkage rotates eccentrically about the second axis upon rotation of the drive member.

Preferably the drive member is moveable relative to the driven member so that the orientation of the first and second axis can be varied, whilst maintaining a substantially parallel relationship.

Preferably the guide means includes a substantially radially extending slot and the linkage includes a follower which is received in the slot. The slot may be formed with curved or sinusoidal portions, as required. Preferably, the follower is adapted to be located at different radial positions relative to the first axis.

Preferably the drive member is mounted to revolve about the second axis.

Preferably the drive member is mounted in a journal, offset from a rotational axis of the journal and the journal is mounted coaxially with respect to the driven member.

Preferably the journal is mounted in a sleeve assembly which is keyed to the driven member.

As can be appreciated, the eccentric motion of the linkage results in the follower being spaced from the second axis by varying distances during revolution of the driven member and this accordingly varies the torque transmitted to the driven member for a given input drive force. The spacing between the first and second axis can also be varied according to torque requirements so that, for example, torque can be maximised for a particular range of revolution of the drive member which corresponds with a power stroke of a drive means coupled to the drive member. Alternatively, when torque requirements are at a minimum, for example, at high speed transmission, the mechanism can be arranged such that the power stroke occurs when the follower is closest to the second axis, thereby providing for a maximum speed ratio between the two members. The variation in the speed ratio can be enhanced further by altering the radius of rotation of the follower relative to the first axis. In the case where the speed ratio is maximised for a certain portion of revolution of the drive member a free wheel assembly may perhaps also be included in the mechanism so that the lower speed ratio for the remainder of the revolution does not adversely affect the output speed of the driven member.

The invention is more fully described, by way of non-limiting example only, with reference to the accompanying drawings which:

Figure 1 is an exploded partial perspective view of the mechanism in accordance with the present invention;

Figure 2 is an exploded side view of a mechanism in accordance with another aspect of the present invention;

Figure 3 is a diagrammatic end view of the mechanism of Figure 1 viewed along the line 3-3, shown in Figure 2;

Figure 4 is an end view representing the mechanism in a first condition;

Figure 5 is an end view similar to that shown in Figure 4, representing the mechanism in a second condition;

Figure 6 is an end view of the mechanism, similar to that shown in Figure 3 representing the mechanism in a third condition;

Figure 7 is an end view of the mechanism, similar to that shown in figure 3 representing the mechanism in a fourth condition;

Figure 8 is an end view of the mechanism, similar to that shown in figure 3 representing the mechanism in a fifth condition;

Figure 9 is an end view of the mechanism, similar to that shown in figure 3 representing the mechanism in a sixth condition;

Figure 10 is an end view of the mechanism of Figure 1 , including a curved guide channel;

Figure 1 1 is a view similar to that shown in Figure 9, showing the mechanism in a further condition; and

Figure 12 is an exploded side view of a modified mechanism, in accordance with the present invention;

A drive mechanism 1 is shown in Figure 1 as comprising a drive member 2, a driven member 3 and linkage 4 in the form of a follower 5 which is received in a guide slot 6 of the member 3 to thereby interconnect the drive and driven members 2, 3. The drive member 2 has an axis of rotation 7 which is arranged in a substantially parallel spaced apart manner with respect to an axis of rotation 8 of the driven member 3.

In use of the mechanism 1, a driving force is applied to the drive member 2 so that the follower 5 executes circular motion about the axis 7 and simultaneously causes the member 3 to rotate as a result of the interconnection via linkage 4. The path of rotation travelled by the follower 5 is shown by phantom lines 5a. As can be seen, the path of rotation of the follower is eccentric with respect to the axis 8. As such, the follower 5 will be forced to travel along the slot 6 during rotation and, accordingly, the distance between the follower and the axis will vary during revolution of the member 3. The variation in the distance will result in corresponding variation in the torque applied to the driven member 3 and the speed ratio between the members, for a constant predetermined torque applied to the drive member 2.

The eccentric motion of the follower 5 relative to the second member 3, and thereby the abovementioned variation in distance, results from the spacing of axis 7 relative to the axis 8. As such, particular torque conditions can be provided by suitable orientation of member 2 relative to member 3, as required. For example, the members may be arranged such that the greatest distance between the follower and the axis 8 is provided simultaneously with a power stroke of a drive means (not shown) which provides the drive force to member 2. whereby to maximise torque transfer. Alternatively, when torque requirements are at a minimum, for example, at high speed transmission, the mechanism can be arranged such that the power stroke occurs when the follower is closest to the second axis, thereby providing for a maximum speed ratio between the two members. The variation in the speed ratio can be enhanced further by altering the radius of rotation of the follower relative to the first axis. In the case where the speed ratio is maximised for a certain portion of revolution of the drive member a free wheel assembly

may perhaps also be included in the mechanism so that the lower speed ratio for the remainder of the revolution does not adversely affect the output speed of the driven member.

The example shown in Figure 1 illustrates an arrangement whereby the drive member is in the form of a shaft 9 and the driven member is in the form of a wheel 10 which transfers its turning motion via a belt 1 1 arranged around the periphery thereof. However, other arrangements are equally suitable such as, for example, both members 2 and 3 can be in the form of gears or the driven member 3 may be connected directly to a driven shaft (not shown). Other embodiments of the invention are shown in Figures 2 and 12 and more detailed description of additional features and advantages of the invention are described below with reference to these embodiments.

The embodiment of the mechanism 20 shown in Figure 2 includes parts providing a similar function to parts described with reference to Figure 1 and, where appropriate, these are indicated by the same reference number. The mechanism 20 includes a drive member 2 in the form of shaft 21 and a driven member 3 in the form of disc 22. The shaft 21 has a linkage 4 secured to one end 23 thereof. The linkage includes a radially extending arm 24 and a follower 5 coupled to the end 25 thereof. The follower 5 is received in slot 6 to interconnect the members 2 and 3 for rotation in sympathy. The mechanism also includes a journal 26 housed in a sleeve 27 which extends concentrically from the disc 22. The shaft 21 is located in a correspondingly shaped lengthwise recess 28 formed in the journal. The journal 26, when mounted in the sleeve 27, is arranged coaxially with respect to axis 8 and is adapted to rotate within the sleeve 27 so that the shaft 21 can be revolved about the axis 8 whilst the axes 7 and 8 remain in substantially parallel spaced relation. The journal 26 also includes attachment means, such as lug 29, for coupling to a suitable device for effecting rotational movement of the journal 26 within the sleeve 27, although the journal is also adapted to be fixed in position, when required.

In one non limiting application and in order to explain the operation of the invention reference is made to Figure 3, which represents, for the purpose of illustration, only the outer perimeter of the disc 22 when viewed in a direction indicated in Figure 2 by the

line 3-3. If the journal 26 is rotated such that the axis 7 of shaft 21 is on and perpendicular to the 270 degree radial from the axis 8 of disc 22, and if radial arm 24 is at zero degrees relative to axis 7 then the arm will intersect radials of the disc 22 falling between greater than 270 degrees and less than 360 degrees. Conversely, if radial arm 24 is at 180 degrees relative to axis 7 then it will intersect radials of the disc 22 falling between greater than 180 degrees and less than 270 degrees. As such, moving radial arm 24 through the arc zero degrees to 180 degrees will cause the disc 22 to rotate through greater than 180 degrees of arc. If radial arm 24 is then moved through the arc 180 degrees to 360 degrees the disc 22 will be caused to rotate through the remaining portion of 360 degrees which is less than 180 degrees. If then the journal 26 is caused to rotate such that the axis 7 of shaft 21 is on the 90 degree radial then it can be seen that moving radial arm 24 through the arc zero degrees to 180 degrees will cause disc 22 to rotate through less than 180 degrees of arc and the subsequent movement of radial arm 24 through the remaining 180 degrees of arc will cause the disc 22 to move through its remaining portion of 360 degrees of arc which is greater that 180 degrees. It can therefore be appreciated that a range of effects can be obtained by altering the radial of the disc 22 upon which the axis 7 of shaft 21 and therefore the axis of the radial arm 24 is positioned. The effect can be further modified by having means to adjust the radius of the arc of the follower 5 and also by having a multiplicity of slots 6 of various contour or sinusoidal form radiating about the face of the disc 22 and into which the connecting means 5 may be selectively mated.

One non limiting practical application of the invention is to provide between design or configuration extremes a continuous range of drive ratios on, for example a bicycle. In such an application one assembly as described above would be mounted on the bicycle in such a manner that one radial arm 24 would occupy the same position as a normal pedal crank and a second assembly would be mounted so that the radial arm 24 of a second assembly would occupy the same position as a second pedal crank. Pedals would be attached to the radial arms 24 and the two discs 22 and sleeves 27 connected so as to rotate in unison. Teeth would be cut into the circumference of disc so as to provide for chain drive. A lever or connecting rod or cable could be provided so as to provide for rotation of each of the journals 26 in such a manner that they both maintain similar relationship to each other such that each shaft 21 is coaxial.

In another non limiting practical adaptation it can be seen that shaft 21 could be an extension of or driven by the crankshaft of a single cylinder internal combustion engine (not shown). In this adaptation a preferred configuration would provide that the disc 22 provide the mass of a flywheel.

Without departing from the scope of the invention it will be seen by one skilled in the art that there are many configurations in which the invention could be constructed and applied.

For a simplified explanation of the foregoing it should first be pointed out that both shaft 21 and disc 22 are effectively joined together by linkage 4 mating with radial slot 6 and therefore must complete a single revolution at the same time as each other and, there does not, therefore appear to be any overall drive ratio present in the present invention. However, drive ratio does exist for some portion of revolution of the shaft 21. In order to understand the manifestation of the drive ratio in the present invention it is first necessary to consider the application examples set out above, these examples were firstly a bicycle and secondly a single cylinder internal combustion engine. For purpose of simplicity first consider the example of a bicycle. While the resultant action of pedalling a bicycle is a rotary action and cursory observation leads one to believe that the action comes from moving ones feet in a circular motion on the pedals, the fact is that the action is derived from the downward motion of the upper leg with the lower leg acting as a push rod and the feet in fact follow the path of the pedals which move in a rotary action as a result of the reciprocating action of the upper leg. In other words all of the energy in pedalling a bicycle is transmitted during one half of each revolution of each pedal. As a result of this fact in order to obtain drive ratios with such an action it is only necessary to alter the radial distance at which the disc 22 is engaged by the shaft 21. For example, a high speed drive ratio is achieved by minimising the distance. Such alteration may also provide a mechanical advantage or disadvantage during that half of a revolution that the power is applied to such a system. The degree of mechanical advantage present or absent on the redundant, return or coasting half of a revolution is for the sake of this discussion omitted. (More on this point later). Consider now Figure 3, and Figure 4, in each of these diagrams the outer circle represents the periphery of disc 22 which on the case of a bicycle would be the front or drive sprocket, the inner circle concentric with the outer

circle represents the end of journal 26 the radial line 6a originating at the centre of each diagram is the radial upon which the radial slot 6 is formed in the face of disc 22, and the vertical line 24a originating on the 90 degree radial is the centreline of radial arm 24 which in the case of a bicycle would be the foreshortened centre line of a pedal crank at top dead centre in Figure 3 and bottom dead centre in Figure 4. The point at which the centrelines 6a, 24a of radial arm 24 and radial slot 6 meet is the point at which follower

5 is received into radial slot 6 and with movement acts upon the wall or side of radial slot

6 to transmit energy and motion to disc 22. The circle shown by dashed line 5a indicates the path which is executed by the follower 5 during revolution of the shaft 21. In diagrams Figure 3 and Figure 4 journal 26 is positioned so that the axis 7 of shaft 21 and hence radial arm 24, or in the case of a bicycle the axis of a pedal crank, is positioned on the 90 degree radial of disc 22. Following now the action which occurs when radial arm 24 is moved in a clockwise direction, as viewed about its axis 7 from the position depicted in Figure 3 to the position depicted in Figure 4, for the construction in this example the follower 5 is at a fixed radius from the axis of radial arm 24 and as the connecting means is free to slide in a radial direction within radial slot 6 it can be seen that with revolution of the assembly the radius of the radial slot 6 between its axis and its point of intersection with radial arm 24 varies during revolution in that it decreases during the first 90 degrees of revolution of radial arm 24 and increases with the second 90 degrees. Assuming a constant angular velocity or axial speed of radial arm 24 it can also be seen than the angular velocity or axial speed of disc 22 increases during the first 90 degrees of revolution of radial arm 24 and decreases during the second 90 degrees. In addition it will be observed that as the point of intersection of radial arm 24 and radial slot 6 was in the 270 degree to 360 degree quadrant of disc 22 at the beginning of the stroke and finished within the 180 degree to 270 degree quadrant the angular distance traversed by disc 22 was greater than the 180 degrees traversed by radial arm 24. If then we observe the action which occurs when radial arm 24 completes its circle, during the return stroke, from the position depicted in Figure 4 to the point depicted in Figure 3 we observe that the effect on the varying radius and angular velocity is the reverse of that observed in the first 180 degrees of revolution. As such, some free wheel mechanism (not shown) may be provided so that the reduced speed of the disc 22 during the return stroke does not adversely affect the speed of, for example, the bicycle.

If now we consider Figure 5 and Figure 6 which has had the journal 26 rotated through 180 degrees so that the axis 7 of shaft 21, radial arm and follower 5 is on the 90 degree radial of disc 22 and again, for the purpose of understanding, radial arm 24 begins at top dead centre as depicted in Figure 5 and moves clockwise through its power stroke to bottom dead centre as depicted in Figure 6. Without the exhaustive run through of effects as above it can be readily seen that each of the effects now observed are opposite to that observed in the previous configuration. Such a configuration, therefore provides a lower speed ratio for higher torque performance. With the effects of these two configurations in mind it can seen that during the power stroke of the pedal of the bicycle which equates to the first 180 degrees of revolution of radial arm 24 there is manifest at the point of intersection of the radial arm 24 and radial slot 6 a lesser mechanical disadvantage in the second configuration than in the first. Having seen that these ratios are present during the power stroke it can also be seen that any mechanical advantage or disadvantage which manifests itself during the power stroke is not lost or negated during the return stroke or up stroke of the pedals as there is no load on the pedals during this half of the revolution of the assembly. It is true that the pedal assembly is accelerated during the first 90 degrees of return stroke however the momentum of inertia imparted is returned during the second 90 degrees of the return stroke.

Having considered the foregoing simplified explanation it is now left to consider the effect where the journal 26 has been rotated so that the axis of shaft 21, radial arm 24 and follower 5 is on either the 0/360 degree radial or the 180 degree radial of the flange 4. Figure 7 depicts the situation where the said axis 7 is on the 0/360 degree radial however for understanding on this example the pedal crank or radial arm 6 has been drawn at the 90 degree point of its rotation in the power stroke. Again without exhaustive explanation it can be readily seen that the effect in this configuration is that the angular velocity of disc 22 continues to increase during the entire power stroke and decreases during the entire back stroke, in addition it is readily observed while there is a 1 to 1 ratio over the entire 180 degrees of the power stroke the angle of the sector described by the sweep of the radial slot 6 is at all times less than the angle of the sector described by the sweep of the radial arm 24 until the point of 180 degrees of sweep when they are both equal. It is also readily observed that mechanical disadvantage manifest at the intersection of radial slot 6 and radial arm 24 increases during the 180 degree power

stroke. Again for the same reasons mentioned above any advantage or disadvantage of the stroke is not negated during the back stroke.

Finally in the bicycle example we now consider Figure 8 where the journal 26 has been revolved within the assembly so that the axis 7 of shaft 21 and related components is on the 180 degree radial of disc 22. Again the pedal crank or radial arm 24 has been depicted at 90 degrees of its power stroke. In this example again it is seen that there is an overall 1 to 1 ratio over the entire 180 degree stroke however in this configuration the angular velocity of disc decreases over the complete 180 degree stroke. Again at all times during the stroke the angle of the sector described by the sweep of radial slot 6 is greater than the angle of the sector described by the sweep of the radial arm 24 however they again become equal at the 180 degree point. In this configuration it is observed that mechanical disadvantage manifest at the point of intersection of radial slot 6 and radial arm 24 decreases during the entire power stroke. The previously described effect on the backstroke remains true in this configuration.

The effect of the mechanism in other, continuously variable stages, between the four configurations described is easily understood by following the logic and sequence set out in describing the previous four configurations.

Now it is important to consider the invention insofar as it applies to internal combustion engines of conventional design for explanation we shall consider a single cylinder, two stroke engine, a single cylinder four stroke engine and a two cylinder four stroke engine.

It is equally true of internal combustion engines as it is of bicycles that there is in relation to each cylinder a power stroke and a return stroke, in four stroke engines there is interposed between these two strokes an exhaust stroke and an intake stroke. In the case of engines it is preferable that the invention be interposed between the engine and the flywheel of the engine and in the preferred configuration the disc 22 would provide the mass of the flywheel. Considering the abovementioned engine configurations in order it is clear that with a two stroke engine there is a power stroke followed by a return stroke which is also a compression stroke. The effect of the power stroke is exactly the same as discussed for the bicycle and all that is left to consider is the return or compression

stroke. Unlike a bicycle (ideally ridden) there is a load against the back or return stroke and this load is present due to the work of returning the piston and connecting rod and also compressing the new charge. In returning the piston and connecting rod and compressing the fresh charge there is a certain amount of work done and therefore energy expended however the sum of the work is not increased or decreased due to the increase or decrease of mechanical advantage on the back stroke. The net energy expended to complete the back stroke remains the same as would be expended in a conventional system, it is merely completed over a greater or lesser time according to ratio manifest on the backstroke by the action of the flywheel acting thought the invention to drive the backstroke. In a single cylinder two stroke engine there is only one non power stroke per revolution hence only that stroke is effected however in a single cylinder four stroke engine there are three non power strokes between power strokes however the underlying principal discussed in respect to the return stroke of both a bicycle pedal and the return stroke of a two stroke engine remains true in respect of the three non power strokes of a four stroke engine, i.e the work performed on those strokes by the flywheel remains constant regardless of the ration between the flywheel and the engine the non power strokes merely occur at a faster or slower rate than would occur without the invention interposed between the engine and the flywheel. The underlying principal is that a power stroke or pulse of the input device correspond to a portion of a revolution of shaft 21.

After considering the above it is also seen that the invention has equal application where the power input is from a smooth source but the output is applied to a pulsed load or any load analogous to a stroke for example the invention could be interposed between an electric motor and a compressor or pump or any application where there is a load for a proportion of a cycle but not the remainder. In the case where a smooth power source is driving a pulsed load the preferred configuration would provide for the flywheel (if any) as is effectively the case with the armature of an electric motor to be on the drive side of the invention.

Two modifications may be made to the simple action described above, these modifications involve provision of sinusoidal or contoured radial slots 6 and altering or adjusting the radius of the point of intersection of radial arm 24 and radial slot 6 by changing the radius of the arc described by follower 5. While there are clearly many means of causing

change in the arc described by follower 5 and also having means to cause a constantly changing radius of arc during rotation I will describe one means only of changing radius of arc and only discuss the effect of a change of radius of arc where the radius of arc remains constant during revolution with an understanding from this effect that the effect of a radius of arc which changes during revolution is readily deduced. Firstly one method of inducing a constantly changing arc is to provide a radial slot in radial arm 24 so that follower is free to slide within that slot, and then possibly also having a sinusoidal guiding means interposed between radial arm 24 and the plane of the face of disc 22 so that follower 5 is caused to slide within the radial slot in radial arm 24 during revolution. An understanding of a change in radius of the arc described by follower 5 is best understood by again considering Figure 3 and Figure 4. Consider first the effect of a lesser radius of arc of the follower 5 than that depicted in Figure 3 and Figure 4. It is seen that at the starting point of a half revolution of radial arm 24 provided with a lesser radius of arc will cause the point of intersection of radial arm 24 with radial slot 6 to fall upon a radial of disc 22 which is closer to its 270 degree radial than the radial depicted in Figure 3 and similarly at the finishing point depicted in Figure 4 that radial would be closer to the 270 degree radial than that depicted. It is therefore seen that in that configuration a decrease of radius of arc of follower 5 will cause disc 22 to rotate to a greater extent. Now considering Figure 5 and Figure 6 it is readily observed that the opposite effect occurs in that disc 22 will be caused to rotate to a lesser extent. The net result then of a reduction in radius of arc of follower 5 is to cause an increase in range of ratio by increasing the ratio at one extreme and decreasing the ratio at the other extreme. It is clear that an increase in radius of arc of follower 5 will have the opposite effect. The effect of an increase or decrease of radius of arc of follower 5 during intermediate points between the two extremes can be readily deduced by reference to Figure 7 and Figure 8 and using the same logic.

The next consideration is the effect of a curved or sinusoidal form of radial slot 6. For this consideration we will discuss the effect of a constant curve and an understanding of this effect will enable the effect of a convoluted or other sinusoidal curve to be deduced. With reference to Figure 9 and Figure 10 it will be seen that with revolution the point of intersection of radial arm 24 and the curved slot 6 in disc 22 moves towards the axis 8 of disc 22 during the first 90 degrees of revolution and away during the second 90

degrees and finishes at the same distance from the axis as it began. However, during revolution the radial of disc 22 upon which the intersection occurs changes with revolution so that with the curve oriented in the direction depicted it can be seen that the effect is to slow the relative angular velocity of disc 22 during the first 90 degrees of revolution of radial arm 24 and increase it during the second 90 degrees. If the curve is oriented in the opposite direction it will be seen that the opposite effect occurs in that the relative angular velocity increases during the first 90 degrees of revolution of radial arm 24 and decreases during the second 90 degrees. Having considered the above one can deduce the effect of a curved radial arm with a slot in it as described above when used with means to alter the radius of the arc described by follower 5.

As can be seen by using one or more of the possible modifications, it is possible to obtain an infinite range of effects.

Again, it can be appreciated that it is possible to construct the invention in many forms. For example it is possible to have a drive shaft through the centre of journal 26 and shaft 21 driven from that drive shaft by means of toothed cogs on each and initial fixed ratio introduced at that point.

In addition it can also be seen that without departing from the scope of the invention it can be used as a device to change a rotary action containing a regular pulse to a smooth rotary action, in other words by interposing the invention between a pulsed input and an output shaft one can eliminate irregularities of revolution at the output shaft.

Having now explained both the principle and the operation of the invention it is also apparent that by altering the configuration of the system with the various means available and discussed it is possible to alter the point in a revolution of shaft 21 at which the greatest or least mechanical advantage is manifest. Considering this in the example of a bicycle it is obvious that the invention would enable adjustment so that the greatest possible efficiency is obtained having regard to the effort applied to the pedals, i.e. one rider may well having regard to his particular circumstance be able to apply the greatest effort at the top portion of a stroke whereas another rider may well be able to apply his greatest effort at the lower portion of a stroke. This principal remains true in the

application of internal combustion engines insofar as with regard to stroke length, timing of both spark and valve the invention can be configured to obtain the maximum advantage and efficiency from a stroke.

Having regard to the underlying principle, that a power stroke corresponds to a portion of a revolution of shaft 21 it is also true that one need only correlate the most efficient or desirable portion of stroke of an input device to the most efficient or desirable portion of a revolution of shaft 21 hence in a multi cylinder engine where there are portions of multiple power strokes concurrently present one can correlate the most advantageous proportion of rotation of shaft 21 to correspond to the concurrent power stroke or proportion of concurrent power stroke from which the most benefit can be derived. Alternatively, as described in the first given bicycle example, where a separate assembly of the invention was provided for each pedal a separate assembly could be provided for each cylinder or group of cylinders. For example consider a six cylinder engine, the engine could be divided into essentially three parts each of two cylinders without connection between three separate crankshafts except through the interposing of three assemblies of the invention driving a common or single drive shaft, while it is pointless to describe in detail such a configuration it is readily obvious that there are a great variety of possible constructions however for the sake of simple explanation consider three separate two cylinder engines placed in line each driving a shaft 21 of the invention which has been mounted on the side of the crankcase of each and in turn the perimeter of each of the discs 22 could be meshed to or driving a single shaft to which the power of the engines is ultimately transmitted. In addition to the above modifications, any one of three further improvements described below may also be employed.

The first of these improvements relates to minimising the smallest distance between the axis 8 and follower 5. In the description of the embodiment shown in Figure 2, it is clear that radial slot 6 had a minimum radius due to the fact that it could not extend in towards the axis 8 beyond the point that it would impinge upon the circumference of journal 26, this limitation in turn limited the minimum radius of arc of follower 5. To overcome this limitation and to gain the advantages due to a small radius of arc of the follower 5, (as described above), there is provided the following embodiment described with reference to Figure 12. The mechanism 30 of Figure 12 includes many components similar to those

of mechanism 20, described with reference to Figure 2, and like parts are denoted with the same reference numeral, the difference in construction resides in the disc 22 being arranged in spaced relation with respect to the sleeve 27 and journal 26. The disc 22 is, instead mounted to a flange 31, which extends radially of the sleeve 27, via a cylindrical collar 32. The linkage 4 is also modified in that the follower 5 is located on an opposite side of the arm 24 so as to engage in slot 33 from a reverse direction to that shown in Figure 2. As can be appreciated, in such an arrangement the length of the slot 33 is not limited by the diameter of the journal 26, thereby allowing a minimum radius of arc of the follower 5 about the axis 8 to be achieved.

The second improvement relates to the changing of ratio manifest by the mechanism when there is a requirement to maintain the spacing of, for example, the axes 7 in relation to the axis of drive or driven shafts (not shown) forming other parts of a power train. As previously discussed the arrangement of the mechanism can be such as to maximise speed ratios to correspond to a power stroke or portion of power stroke. Previously described were two means of changing ratio manifest, the first in relation to the bicycle example involved rotating journal 26 about it axis, the second as discussed in relation to internal combustion engines may involve rotating the journal 26 about the axis 7 of shaft 21. The rotation of journal 26 about the axis 7 shaft would alter the position of the axis 8 of disc 22 in relation to a power train and, in order to compensate for such a change in axis position there may be provided, attached to outer face 34 of disc 22, a ring gear coaxial with disc 22 and having its teeth oriented inward and the meshing point on the extended axis of shaft 21. Alternatively the whole assembly may be arranged to maintain a fixed axis 8 and a coupled pair of epicyclic gears may instead be provided, one on the end of shaft 21 and one on a shaft driving shaft 21 or driven by shaft 21 such that with movement of the outer ring of one or both of the sets of epicyclic gears is rotated one way or the other in relation to its coupled shaft and so the orientation of the various points of ratio or moment of the system is moved in relation to the stroke.

The third improvement is the addition of a gear train to the system, as with any system of gearing or torque conversion there are limits to the ranges available, this is true of the present invention however the mere addition of a conventional gearbox to the power train would be a somewhat self defeating process. As the present invention while not altering

output shaft speed in relation to overall or average crank speed it does continuously alter between design or configuration limits the torque transmitted to the output shaft. The present invention therefore does have an effect analogous to the effect of conventional gears. In order to extend the range or effect it is advantageous to also add a gearbox to the power train, after the flywheel or if the present invention is providing the mass of the flywheel after the present invention as described. This improvement or addition provides for the addition of a gearbox of conventional design except in having steps between ratios that are proportionate to the range of effective gearing provided by the present invention in any particular configuration. For example assume an application in an automobile that normally had a four speed or ratio gearbox. This improvement or addition provides for a gearbox which has its ratios set in sympathy with or take into account the effective range provided by the present invention, for example it may be that with the lowest gear of the gearbox selected and the present invention set at equivalent to low, then the combination of the two effects is equivalent to standard first gear for the subject vehicle type, then with operation the invention setting is moved up through its range to the top a ratio change would then be made in the gearbox while at the same time setting the invention back to its low setting after which the invention would be again moved through its range. In this manner according to configuration and application it is possible to exceed design or configuration settings or limits of the present invention while maintaining a stepless range of transmission ratios while concurrently reducing the complexity and cost of a standard gearbox whether manual or automatic.

As can be appreciated from the above, the inventive concept in any of its aspects can be incorporated in many different constructions so that the generality of the preceding description is not to be superseded by the particularity of the attached drawings. Various alterations, modifications and/or additions may be incorporated into the various constructions and arrangements of parts without departing from the spirit or ambit of the invention.